Among emerging viruses, the Nipah virus is particularly deadly, killing up to 70 percent of the people it infects. That's why Nipah has been declared a potential bioterrorism agent by the National Biodefense Research Agency of the United States. Now scientists have identified the way the virus infects cells, causing often-fatal encephalitis. This discovery could lead to medications and vaccines to prevent or cure the disease.
This virus, which devastated Malaysian pig farms in 1999, attaches to a cell receptor, a kind of chemical doorway, called Ephrin-B2, two teams of U.S. scientists reported this month. Ephrin-B2 is found in humans, horses, pigs, bats and other mammals, which explains the wide number of species that can be infected.
The first reported outbreak of Nipah virus occurred in 1998-1999 in Malaysia, sickening 265 people and killing 105. This outbreak which spread from pigs to humans, was contained by culling more than a million pigs. A related virus, Hendra, so far less of a threat to human health, was first identified in 1994 in Australia when it spread from horses to humans. Both were eventually traced to fruit bats.
The reason that the viruses are on the biodefense priority list is because they are fatal and there is potential for misuse. In its natural state, the Nipah virus can be used as a potential bioterrorism agent capable of devastating an entire country's public health and economy, say anti-terrorism specialists.
In Bangladesh, death rates from repeated outbreaks of Nipah over the past four years have risen to 70 percent. This suggests that the virus may be mutating and becoming more lethal. The more we can learn about the viruses, the better the world will be prepared for another outbreak or for bio-terror, US agencies have said.
The reason the virus suddenly appeared in humans is due to increased contact between bats and humans. Nipah has jumped from bats to livestock and eventually to humans because the habitats of the bats have been disturbed, as I reported in 2002. There are many viruses in the natural world we know nothing about, and disturbing the environment may lead to their rapid transmission. The simple message is: protect our environment and try and live sensibly and in harmony with other species.
By Nirmal Jivan Shah, published on the People Newspaper, Seychelles, on 21 July 2005